Docs: Use US spelling and correct a typing mistake.

This changes two inline comments and a docblock so that they use US spelling as advised by the Core Handbook's Best Practices. A typing mistake is also corrected.

Reference:
- [https://make.wordpress.org/core/handbook/best-practices/spelling/ Core Handbook - Best Practices - Spelling].

Follow-up to [18632], [38120], [44954].

Props kebbet, mukesh27.
See #58833.

git-svn-id: https://develop.svn.wordpress.org/trunk@56825 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/class-wp-filesystem-base.php

@@ -216,13 +216,13 @@ class WP_Filesystem_Base {
 				}
 			}
 		} elseif ( 'direct' === $this->method ) {
-			$folder = str_replace( '\\', '/', $folder ); // Windows path sanitisation.
+			$folder = str_replace( '\\', '/', $folder ); // Windows path sanitization.
 
 			return trailingslashit( $folder );
 		}
 
 		$folder = preg_replace( '|^([a-z]{1}):|i', '', $folder ); // Strip out Windows drive letter if it's there.
-		$folder = str_replace( '\\', '/', $folder ); // Windows path sanitisation.
+		$folder = str_replace( '\\', '/', $folder ); // Windows path sanitization.
 
 		if ( isset( $this->cache[ $folder ] ) ) {
 			return $this->cache[ $folder ];

src/wp-admin/includes/file.php

@@ -1266,7 +1266,7 @@ function download_url( $url, $timeout = 300, $signature_verification = false ) {
 		$signature_verification = in_array( parse_url( $url, PHP_URL_HOST ), $signed_hostnames, true );
 	}
 
-	// Perform signature valiation if supported.
+	// Perform signature validation if supported.
 	if ( $signature_verification ) {
 		$signature = wp_remote_retrieve_header( $response, 'X-Content-Signature' );
 

src/wp-includes/class-wp-http-requests-response.php

@@ -8,7 +8,7 @@
  */
 
 /**
- * Core wrapper object for a WpOrg\Requests\Response for standardisation.
+ * Core wrapper object for a WpOrg\Requests\Response for standardization.
  *
  * @since 4.6.0
  *